Photolithography has hitherto been adopted for formation of fine elements or for microfabrication in extensive fields including the manufacture of semiconductor integrated circuits such as LSIs, the preparation of FPD screens, and the production of circuit boards for color filters, thermal heads and the like. In photolithographic processes, positive- or negative-type photosensitive resin compositions are used for resist pattern formation. Those photosensitive resin compositions include positive-type photoresists, such as, a resin composition comprising an alkali-soluble resin and a quinonediazide compound serving as a photosensitive substance. This photosensitive resin composition is commonly employed.
Meanwhile, in recent years, LSIs have been required to be high integration and accordingly resist patterns have been required to be miniaturized. In order to meet the requirement, it is becoming practicable to carry out lithographic processes by use of short-wavelength radiation, such as, KrF excimer laser light (wavelength: 248 nm), ArF excimer laser light (wavelength: 193 nm), extreme ultraviolet light (EUV, wavelength: 13 nm), X-rays or electron beams (EB). In accordance with the miniaturization of patterns, photosensitive resin compositions serving as photoresists in microfabrication are now required to provide patterns with high resolution. Further, they are also required to be improved in other properties, for example, sensitivity, pattern shapes and dimensional accuracy of images, as well as, for the resolution. In view of that, a “chemically amplified photosensitive resin composition” is proposed as a high-resolution radiation-sensitive resin composition having sensitivity to short-wavelength radiation. The chemically amplified photosensitive resin composition contains a compound which generates an acid when exposed to radiation. Accordingly, when exposed to radiation, the acid-generating compound releases an acid and the acid works catalytically to form an image with high sensitivity. Since the advantage of high sensitivity, the chemically amplified photosensitive resin composition is now taking the place of conventional ones and becoming widely used.
However, in accordance with the recent miniaturization of patterns, there is tendency of increasing serious problems, such as, pattern collapse and pattern roughness (line width roughness: LWR, line edge roughness: LER). For the purpose of coping with those problems, it is proposed, for example, to improve the resin compositions by changing the components (Patent documents 1 and 2). Although LER can be improved by the methods disclosed in those documents, it is desired to make further improvement according to further demands for miniaturization.